Method for the finishing treatment of workpieces

Abstract

A method for the finishing treatment of work pieces, uses a processing device including a tool spindle for a processing tool and a numerically controlled (NC) feeding device. The force of the contact pressure applied to the work piece on the side of the work piece is measured and the measured force values are supplied to the numerical control (NC), which determines and fixes the feed rate at which the processing tool is advanced against the work piece. The finishing treatment is carried out in a force-controlled operating mode, in which the feed rate is controlled depending on the force of the contact pressure acting on the processing tool. A processing device is employed whose tool spindle is movably supported in the direction of the feeding movement on leaf springs on the feeding device. The processing device includes a force-measuring device effective between the tool spindle and the feeding device and operating substantially free of deformation. In the force-controlled operating mode, feed rate values are allocated to the values measured by the force-measuring device at a cycle control frequency preset by the numerical control (NC), whereby the allocation is fixed according to a damping function.

What is claimed is:  
     
       1. A method for finishing a work piece at a preset force value comprising the steps of: 
       (a) providing a processing device having a tool spindle for a processing tool movably supported in a direction of feed movement via leaf springs on a feeding device coupled to a numerical control (NC);  
       (b) measuring a contact pressure force applied by the processing tool on a side of a work piece using a force-measuring device disposed between said tool spindle and said feeding device operating substantially without deformation;  
       (c) allocating feed rate values to corresponding measured force values at a cycle control frequency preset by said numerical control; and  
       (d) supplying contact pressure force values to the said numerical control for control of a feed rate at which the processing tool is advanced against the work piece in accordance with a selected damping function for a particular application so that in carrying out a finishing treatment in a force-controlled operating mode the feed rate increases with decrease in measured force value and decreases with increase in measured force value, until the measured force value substantially corresponds with the preset force value.  
     
     
       2. The method according to  claim 1  further comprising: 
       advancing the tool spindle against the work piece at a high-speed rate until an initial cut of the work piece by the processing tool has been recognized by a measuring signal of the force-measuring device;  
       stopping feeding movement of the tool spindle by the numerical control when the initial cut has been recognized; and  
       carrying out further processing in the force-controlled operating mode.  
     
     
       3. The method according to  claim 1  wherein the feeding device comprises a carriage driven by a roller spindle. 
     
     
       4. The method according to  claim 1 , wherein the force-measuring device is a piezo electric element clamped between a connecting element secured on the tool spindle and a bearing block arranged on the feeding device, said piezo electric element transmitting forces of contact pressure acting on the tool to the feeding device substantially free of deformation. 
     
     
       5. The method according to  claim 1 , wherein the feeding device performs a multi-axis feeding movement; and the feeding associated with the axes are controlled by the numerical control (NC) so that a superposed feed takes place in the force-controlled operating mode in the direction in which the force is acting. 
     
     
       6. The method according to  claim 1 , wherein the preset force value for the finishing treatment is varied incrementally or continually in the force-controlled